1. Field of the Invention
The present invention relates to a sound image position correction system that corrects the position of a sound image output from a plurality of speakers in a multichannel reproduction system having three or more channels.
2. Description of the Related Art
As a medium capable of reproducing multichannel having three or more voice channels which are independent of one another, SACD (Super Audio Compact Disc), DVD (Digital Versatile Disc or Digital Video Disc), and the like have been standardized.
For example, in a 5.1 ch surround system which has been developed for creating sound effect that makes a scene alive in a movie theater, six speakers (speakers placed in the front, right-front, left-front, right-rear, left-rear of audience, and subwoofer speaker for bass sounds (in general, placed in the front of audience)) are used to create a special and real sound environment.
As described above, a 5.1 ch surround system in which six speakers (speakers placed in the front, right front, left front, right rear, left rear of audience, and subwoofer speaker for bass sounds (in general, placed in the front of audience)) are used to create a special and real sound environment has been known. Note that the subwoofer speaker can reproduce a limited range of sounds, so that it is counted as 0.1 channel.
In recent years, the 5.1 ch surround system has been applied to DVD-video or digital broadcasting.
In a system constituted only by real speakers, early-reflected sound and reverberant sound are generated from respective speakers placed in a horizontal plane in general, so that it is not possible to create reflected sound from above. However, three-dimensional (3D) sound processing using a DSP (Digital Signal Processor) allows creation of an environment where reproduction sound is heard as if it were output from the position different from the actual speaker position, thereby realizing virtual localization of a plurality of sound sources or controlling the position of a sound image to an arbitrary position in front of audience by virtually shifting the position of a sound image (refer to, for example, Patent Documents 1 and 2: Japanese Patent Application Laid-Open Publication No. 2001-16698 and No. 2004-135023)
Along with the popularization of an LCD display or the like, the thickness of a display unit of a TV set or the like has been reduced but the size thereof has been increased. Such a TV set is located in a conspicuous place in a room in general and serves also as a main interior furnishing item. Further, a display unit serving as a multiple function unit capable of reproducing/displaying video information recorded in various recording media with a large-sized screen has emerged.
Similarly, an audio unit having not only a function of reproducing a sound signal employed in the past but also having a multiple function has emerged. For example, such a multi-functioned audio unit is connected to a display unit to thereby powerfully reproduce a sound signal in accordance with a video image displayed on a large-sized screen of the display unit. Accordingly, there is an increasing demand that a display unit and audio unit are combined to serve as so-called a multiple function unit, that is, an audio/display apparatus.